This invention generally relates to multi-pin, flat cable connectors and more specifically is directed to an improved multi-pin connector for grounding a flat, shielded conductor.
Radio frequency (RF) energy is, in general, an alternating-current energy at any frequency in the radio spectrum between approximately 10 KHZ and 3.times.10.sup.8 MHZ. The higher frequencies are used increasingly primarily because of the availability of smaller components and the requirement for increased signal information rates. This is particularly true in information processing systems where large amounts of information are carried by high frequency signals which are then processed by densely packed, sub-miniature logic circuitry. These high frequency signals tend to escape from their medium of transmission and interfere with surrounding electronic components and conductors. This phenomenon is termed RF interference, the effects of which may vary from rendering electronic equipment totally unusable to periodic performance inaccuracies in high speed signal processing equipment.
RF interference is particularly troublesome in an information processing system such as a word processor. In a typical word processor pulsed signals at 5-10 MHZ are used to drive various sub-systems including several levels of logic circuitry and video display electron beam drive circuitry. These high frequency pulsed signals have extremely rapid rise rates and generate harmonics which interfere particularly with the VHF reception band of nearby television receivers at 54-60 MHZ. In addition, the picture carrier signal in a conventional television receiver operates at 55.25 MHZ which is also subject to RF interference as evidenced by the commonly observed "herringbone" effect on the television receiver's video display.
The degrading effects of RF interference on a television receiver can be partially alleviated through the use of coaxial and twin lead antenna conductors. But this only reduces the effects of RF interference without completely eliminating them since the antenna itself is still susceptible to receiving interfering signal inputs. In particular, a television receiver employing a rabbit ears-type of antenna installation remains highly susceptible to RF interference.
To reduce the effects of RF interference on television receivers and other high frequency electronic devices, conductors carrying these potentially interfering signals have been increasingly enclosed in conductive shields. By coupling these grounded shields to neutral ground potential, RF signals are effectively confined therein and directed to ground. In addition, electronic apparatus in which the high frequency signals are processed are frequently provided with an internal grounded surface for reducing the propagation for high frequency signals therefrom. There remains, however, a potential source of RF signal leakage from these systems and that is at the interface between the external conductor and the grounded enclosure of the electronic device. Prior art devices have frequently coupled a single grounded pin in a multi-pin conductor to the shield for grounding purposes. But this method of grounding has suffered from limitations primarily because of the limited area of electrical contact employed therein. The present invention is intended to overcome the aforementioned problems by providing an effective ground coupler for the shield of an external conductor connected to the panel of an electronic device.